rc4.java

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// $Id: RC4.java,v 1.1.1.1 2002/08/27 12:32:10 grosbois Exp $
//
// $Log: RC4.java,v $
// Revision 1.1.1.1  2002/08/27 12:32:10  grosbois
// Add cryptix 3.2
//
// Revision 1.5  2000/08/17 11:40:51  edwin
// java.* -> xjava.*
//
// Revision 1.4  1998/04/03 07:23:55  kettler
// Made sBox and x, y non-static to allow more than one
// instance to be used at the same time.
//
// Revision 1.3  1997/11/29 04:42:56  hopwood
// + Changes to engineUpdate method.
//
// + Added inLen parameter to native_crypt.
//
// Revision 1.2  1997/11/20 19:31:40  hopwood
// + cryptix.util.* name changes.
//
// Revision 1.1.1.1  1997/11/03 22:36:56  hopwood
// + Imported to CVS (tagged as 'start').
//
// Revision 0.3.2.0  1997/09/18  David Hopwood
// + Rewrote engineUpdate, and moved the RC4 algorithm into a separate rc4
//   method. A temporary array is no longer needed except when the input and
//   output regions overlap.
// + Native linking and debugging are up to date with Blowfish 3.2.0
//   (hence the jump in version number).
//
// Revision 0.1.1.1  1997/08/28  David Hopwood
// + Documentation changes.
//
// Revision 0.1.1.0  1997/08/19  David Hopwood
// + Added native support API.
// + Made BLOCK_SIZE private.
// + Ensured that this class is final, and added a comment that this is for
//   security reasons.
//   If it were not final, some VMs have a bug that would allow a subclass
//   that implements Cloneable to call Object's or Cipher's clone() method
//   using invokenonvirtual, which would duplicate the pointer to the native
//   state. Then calling finalize() on the original and using the clone (for
//   example) would result in freed memory being written to :-(.
//
// Revision 0.1.0.0  1997/07/15  R. Naffah
// + Original version.
//
// $Endlog$
/*
 * Copyright (c) 1997 Systemics Ltd
 * on behalf of the Cryptix Development Team.  All rights reserved.
 */

package cryptix.provider.cipher;

import cryptix.util.core.Debug;
import cryptix.CryptixException;

import java.io.PrintWriter;
import xjava.security.Cipher;
import java.security.Key;
import java.security.KeyException;
import java.security.InvalidKeyException;
import xjava.security.SymmetricCipher;

/**    
 * This class implements the RC4 (TM) stream cipher.
 * <p>
 * The source code (C version) from which this port was done, is the one
 * posted to the sci.crypt, alt.security, comp.security.misc, and
 * alt.privacy newsgroups on Wed, 14 Sep 1994 06:35:31 GMT by
 * "David Sterndark" &lt;[e-mail]&gt;
 * (Message-ID: &lt;[e-mail]&gt;)
 * <p>
 * RC4 (TM) was designed by Ron Rivest, and was previously a trade secret of
 * RSA Data Security, Inc. The algorithm is now in the public domain. The name
 * "RC4" is a trademark of RSA Data Security, Inc.
 * <p>
 * <b>References:</b>
 * <ol>
 *   <li> Bruce Schneier,
 *        "Section 17.1 RC4,"
 *        <cite>Applied Cryptography, 2nd edition</cite>,
 *        John Wiley &amp; Sons, 1996.
 * </ol>
 * <p>
 * <b>Copyright</b> &copy; 1997
 * <a href="http://www.systemics.com/">Systemics Ltd</a> on behalf of the
 * <a href="http://www.systemics.com/docs/cryptix/">Cryptix Development Team</a>.
 * <br>All rights reserved.
 * <p>
 * <b>$Revision: 1.1.1.1 $</b>
 * @author  Raif S. Naffah
 * @author  David Hopwood
 * @since   Cryptix 2.2.2
 */
public final class RC4 // must be final for security reasons
extends Cipher
implements SymmetricCipher
{

// Debugging methods and vars.
//...........................................................................

    private static final boolean DEBUG = Debug.GLOBAL_DEBUG;
    private static final boolean DEBUG_SLOW = Debug.GLOBAL_DEBUG_SLOW;
    private static final int debuglevel = DEBUG ? Debug.getLevel("RC4") : 0;
    private static final PrintWriter err = DEBUG ? Debug.getOutput() : null;
    private static void debug(String s) { err.println("RC4: " + s); }


// Native library linking methods and vars.
//...........................................................................

    private static NativeLink linkStatus = new NativeLink("RC4", 2, 3);
    public static cryptix.util.core.LinkStatus getLinkStatus() { return linkStatus; }

    /**
     * The native reference to the current native key schedule
     * structure. Defaults to 0 but is set by native code after a
     * successful call to native_init().
     * <p>
     * IMPORTANT: Do not change the name of this variable without
     * duplicating the same in the native code.
     */
    private long native_cookie;

    /**
     * This object must be synchronized on while calling any native instance
     * method. It is null if the native code is not being used (e.g. the
     * library did not load successfully, or the user disabled its use in
     * the properties file).
     */
    private Object native_lock; // defaults to null

    private void link() {
        synchronized(linkStatus) {
            try {
                if (linkStatus.attemptLoad()) {
                    linkStatus.checkVersion(getLibMajorVersion(), getLibMinorVersion());
                    linkStatus.check(native_clinit());
                }
                if (linkStatus.useNative()) {
                    linkStatus.check(native_init());
                    native_lock = new Object();
                }
            } catch (UnsatisfiedLinkError e) {
                linkStatus.fail(e);
if (DEBUG && debuglevel > 2) debug(e.getMessage());
            }
if (DEBUG && debuglevel > 2) debug("Using native library? " + (native_lock != null));
        }
    }


// Native support API
//...........................................................................

    // The methods that get the library version.
    private native static int getLibMajorVersion();
    private native static int getLibMinorVersion();

    /**
     * Static initialization and self-test method for the native code.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_clinit();

    /**
     * Initializes the native state for this cipher object and allocates
     * needed native storage for the internal key schedule. A reference
     * to the newly allocated space, if successful, is stored in the
     * instance variable <code>native_cookie</code>.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_init();

    /**
     * This function expands the user key to an internal form.
     *
     * @param cookie    a valid reference to the native key structure. This
     *                  value is set by the native library upon return from
     *                  native_init() (see link() method at the top).
     * @param userKey   a byte array representing the user key
     * @return an error String, or null if there was no error
     */
    private native String native_ks(long cookie, byte[] userKey);

    /**
     * Encrypts/decrypts an array. For stream ciphers, encryption is the same
     * process as decryption.
     * <p>
     * SECURITY: the caller <strong>must</strong> ensure that:
     * <ul>
     *   <li> <code>in != null</code>
     *   <li> <code>out != null</code>
     *   <li> <code>inOffset >= 0</code>
     *   <li> <code>(long)inOffset + inLen <= in.length</code>
     *   <li> <code>outOffset >= 0</code>
     *   <li> <code>(long)outOffset + inLen <= out.length</code>
     * </ul>
     *
     * @param  cookie       a valid reference to the native key structure. This
     *                      value is set by the native library upon return from
     *                      native_init() (see link() method at the top).
     * @param  in           input array containing data to encrypt/decrypt.
     * @param  inOffset     index of where we should start reading from input.
     * @param  inLen        number of bytes to encrypt/decrypt.
     * @param  out          output array containing data encrypted/decrypted.
     * @param  outOffset    index of where we should start writing to output.
     * @return the number of bytes crypted (always inLen) or 0 if an error
     *                      occurred.
     */
    private native int native_crypt(long cookie, byte[] in, int inOffset, int inLen,
                                    byte[] out, int outOffset);

    /**
     * Finalizes the native state for this object.
     *
     * @return a string if an error occurred or null otherwise.
     */
    private native String native_finalize();


// RC4 constants and variables